Few things make Americans more publicly irate than flying. Every day brings a new Twitter rant, and most of them are too unhinged to even be entertaining. On Twitter, the variety of airlines called out as the “worst” is surprising—American, United, Spirit, EasyJet, and even proper old British Airways regularly receive severe condemnation—but at this point, the accompanying vitriol isn’t surprising in the least.

This is not to say that travelers’ complaints aren’t justified. Not too long ago, flying could be a relatively pleasant experience, but executives focused on cutting costs have stripped away everything flyers associated with luxury or even dignity. Food, baggage handling, boarding in a logical manner: Things once taken for granted now must be paid for or done without. Flights are more crowded than they’ve been since World War II, when they were carrying troops. And on a recent Ryanair flight, I discovered that not even water was free.

So yes, certainly, flying is rough and getting rougher. But so are many things in modern life. Restaurants charge more and offer less. Movie theaters raise prices and force patrons to sit through endless, blaring pre-roll commercials. And, of course, jobs ask more and more of employees, including longer hours and fewer benefits, and yet give less and less in return.

Why is it that the frustrations of airline travel are what makes so many people explode? Why is this particular experience the one that resonates so deeply?

“If I've learned one thing, it's to never underestimate people's contempt for the airlines,” said Patrick Smith, the author of Cockpit Confidential, when I spoke to him. “Where this sentiment comes from is hard to pin down, but it has something to do with the way the air-travel experience has devolved over the years.”

Smith said flying used to be a lot more relaxing. “People are aware of this, even if they aren't old enough to actually remember it. This becomes a form of resentment,” he said.

“This is understandable,” he went on, “but it isn't necessarily fair, because these same people rarely acknowledge the fact that flying has become so much cheaper.” Smith says that about 30 years ago, the average fare was about twice what it is today. “The stresses of flying are duly noted: the security process, our noisy airports, and crowded cabins, etc. But flying is nonetheless affordable, astonishingly safe, mostly reliable—about 80 percent of flights arrive on time—and, all things considered, reasonably comfortable,” he said.

In other words, because bus travel has always been awful, people expect a ride on the Greyhound to be only marginally more bearable than being dragged behind a horse, and so they are not disappointed. Whereas passengers have seen air travel look sexy, even fun, in movies and on TV, which makes the sharp contrast with reality all the more maddening.

Especially since some select passengers do still get the Don Draper experience denied to everyone else: those in first class. And there’s the rub. In most areas of life, Americans can believe the polite fiction that life is fair and that everyone receives relatively equal treatment. My subway train is delayed? So is his.

By contrast, when travelers enter a plane, they are often forced into a shuffling walk of shame past the lucky few who were allowed to board in a leisurely fashion, who didn’t have to fight for overhead space, and who are already sipping complimentary drinks while stretching out in seats that look straight out of Sharper Image.

Perhaps when travelers vent, they are articulating their frustration about having spent a lot on a big-ticket item—flights, after all, aren’t cheap, and flying remains a privilege in the first place—and yet still not being able to buy good treatment. When I spoke to Ritchie King, a reporter for FiveThirtyEight, he called the contemporary airline experience “a surreal business transaction,” akin to having gone out to a restaurant and ordered “Eggs Benedict and paid for it, only to have the server tell you that you'll have to come back the next night for a soggy roasted-vegetable wrap instead.” In few other transactions are the rules quite so Alice In Wonderland-ish.

Or perhaps a complaint on social media is a kind of humblebrag, a backhanded way of announcing, “I am comfortable enough to fly, even though I may not be rich enough to fly in style.”

William McGee, the author of Attention All Passengers, agreed with me that flying evokes our fury—and our usually dormant class rage—like few other experiences. “Things are just fine in business class and first class. I don’t think that’s coincidental. It reflects the larger issues we face as a society right now, the 99 percent vs. the 1 percent. I’ve talked to execs about deteriorating conditions in the back and their response is basically, ‘You should pay for and sit up front,’ which is a bit of a ‘Let them eat cake’ response.”

As McGee succinctly put it, “Flying sucks, but it wasn’t always that way.” Nowadays, he said, “when I travel from Connecticut to Washington to attend a hearing on the airline industry, I take Amtrak.”

Flying brings out our inner toddlers because not only is our own experience so mediocre, but we also see other people getting what we are being denied, perks we retain the memory of receiving ourselves. We can still taste that once-free water.